Mentioned below are key factors and constraints that will impact product components and overall design:

• board should have dimensions of 24x32mm and be compatible with the cheap, sub $10, eBay sourced nRF51822 board (it is a variation of Core51822 with additional quartz). This board provides BLE capability, ARM Cortex M0 CPU and some storage.
• the footprint of 9DOF board, nRF51822 and battery all stacked together should not exceed nRF51822's dimensions
• it should be super power efficient. Hence, every sourced component must be selected against this criterion
• Important part of the device is its storage capability. FLASH chip should take care of permanent storage. Minimum 16MB
• In addition to flash, FRAM chip will be used. This is a very fast nonvolatile memory and does not have limit of repeated writes, thus will ideally suit as a counter storage or buffer memory
• always-on accelerometer chip for low-precision measurements
• 9DOF multi chip module for precise motion detection
• 3.7V Li-Po battery with small footprint

Nice to have:

• SPI expansion socket to include other sensors (ex. barometer )
• for visual feedback a single-colour LED
• for tactile feedback a vibration motor
• button will be used for input

so .... Phase 1 - DONE